Extrusion dies



y 6, 1953 P. BILLEN 2,833,406

' EXTRUSION DIES Filed Feb. 24, 1954 INVENTOP I P L Zer) United States Patent EXTRUSION DIES Peter Billen, Leverkusen-Kuppersteg, Germany, assignor to Schloemann Aktiengesellschaft, Dusseldorf, Germany Application February 24, 1954, Serial No. 412,332 Claims priority, application Germany April 17, 1953 2 Claims. (Cl. 207-17) In extrusion presses for the production of thin-walled tubes, more particularly for the manufacture of cable sheathings, tools have already been proposed the matrix or die of which has an annular projection of preferably acute-angled cross-section, which on the one hand bounds the annular cross-section forming the tube or the cable sheathing, and on the other hand is bounded in a known manner by the end of the mandrel. Through the use of such tools it is possible, with low pressing pressures, to produce tubes of unusually small wall thickness.

The invention applies this principle to extrusion dies for the production of solid or hollow sections with plane wall surfaces, preferably from light metal such as aluminum, in order to obtain such tools as well as the advantage of low pressing pressures and the possibility of producing very thin-walled sections.

The invention consists in providing each plane internal wall surface of the die aperture, on the front surface of the die, that is to say, on the end surface facing the direction in which the material to be extruded will approach the die, with a forwardly projecting acuteangled ridge,

these ridges together entirely surrounding the die aperture, the knife-edge of each ridge being in the plane of its associated internal wall surface, and each knife-edge, extending from one corner to another of the die aperture, being in the form of a concave curve. With the aid of such dies it is possible to press very thin-walled profiles smoothly.

For the production of noncircular profiles some parts of which are at dilferent distances from the centre of the matrix, it has hitherto been the practice, for the purpose of obtaining a uniform flow of material, to provide in the middle region of the matrix so-called brakes, that is to say the rear surface of the matrix has been arched in such a manner that the profile slit near the centre of the matrix is longer than at the sides. Through this arrangement the resistance to the flow of the material under pressure is increased near to or in the matrix centre, so that in view of the fact that the flow of material in the middle longitudinal axis of the receiver is more active than at the sides, a uniform outflow of the material out of the matrix is obtained. The use of such brakes signifies, however, that the total pressing pressure which has to be used must be increased.

According to a further feature of the invention such brakes are avoided and the uniform flow of the material at all parts of the cross-section is obtained by the expedient that the projection on the front side of the matrix, as it becomes lower from the outside to the matrix centre also becomes blunter. Thus, there is no braking action in the middle of the matrix, but as the distance from the middle of the matrix increases the resistance to the flow is gradually reduced.

Patented May 6, 1958 Two constructional examples of the invention areillus trated in the accompanying drawing, in which:

Figures 1 and 2 show the first constructional example; and

Figures 3 and 4 the second constructional example.

Figure 1 shows a plan view of a die or matrix 1 having a square hole 2 through it for pressing a square profile. The front surface 3 of the matrix 1 has a marginal projection 4 which extends around the hole 2 and terminates in a knife-edge 5. Through the employment of such a matrix it is possible to manage with a lower pressing pressure than hitherto.

The matrix according to Figures 3 and 4 shows a. hole 6 for the production of'an extruded bar of angleshaped cross section. If the front surface 7 and the rear surface 8 of the matrix were flat and parallel to one another, the result would be, that at those parts of the hole 6 which lie nearest to the centre 9 of the matrix, the flow of material would be most active, so that no smooth profiles could be produced.

Now, in order to facilitate the flow of material with an increase in the distance from the centre 9 of the matrix the hole 6 is surrounded by an acute-angled ridge 10 the height and sharpness of which decrease towards the middle 9. As Figure 4 shows, the height of the marginal ridge in the middle is about equal to zero at 10a, while the height and sharpness of the marginal ridge increase towards the sides. The flow of material, which in any case becomes worse as the distance from the matrix centre increases, will now be improved by theprovision of the marginal ridges as the distance from the centre increases, so that a uniform flow of material over the entire width of the die aperture results.

It will be clear from the drawings, particularly from Figures 2 and 4, that the knife-edges, such as 5, of the ridges 4 and 10, are in each case located exactly in the plane of the associated wall surface of the die aperture. The invention is limited to extrusion dies in which the die aperture is bounded by plane wall surfaces. I I

I claim:

1. An extrusion die having a die aperture bounded by plane internal wall surfaces, for the production of solid and hollow products with plane surfaces, the die comprising on its front surface, that is to say, on the die surface facing the receiver, a plurality of forwardly projecting acute-angled ridges, one along each edge of the die aperture, the ridges together surrounding the entire front edge of the die aperture, the knife-edge of each ridge being located in the plane of the associated wall surface of the die aperture, and the knife-edge of each ridge having a concave curvature extending from one corner to an adjacent corner of the die aperture.

2. An extrusion die as claimed in claim 1, the acute angle of the knife-edge of each ridge varying according to its distance from the center of the die, being less acute near the center of the die than towards the outside.

References Cited in the file of this patent UNITED STATES PATENTS 515,951 Cobb Mar. 6, 1894 2,341,749 Webb Feb. 15,1944 2,538,918 Sejournet et a1. Jan. 23, 1951 2,753,044 Haendeler July 3, 1956 FOREIGN PATENTS 588,835 France May 25, 1925 715,411 Germany Dec. 20, 1941 

